Three different room temperature ionic liquids (RTILs) namely protonated betaine bis(trifluromethylsulfonyl)imide ([Hbet][Tf2N]), N-butyl-N-methylpyrrolidinium bis(trifluromethylsulfonyl)imide (BMPyTf2N) and N-methyl-N-propylpiperidinium bis(trifluromethylsulfonyl)imide (MPPiTf2N) were synthesized and characterized by CHNS analysis, NMR and FTIR spectroscopy. Heat capacity measurements and thermogravimetric analysis of these RTILs were carried out and the results are reported in this paper.